Homogeneous carbon doping of magnesium diboride by high-temperature, high-pressure synthesis
- Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)
- Center for Advanced Materials Characterization in Oregon (CAMCOR), University of Oregon, Eugene, Oregon 97403 (United States)
We have used high-pressure, high-temperature synthesis at 1500–1700 °C and 10 MPa to create homogeneously C-substituted MgB{sub 2} from a B{sub 4}C + Mg mixture. X-ray diffraction analysis showed large peak-shifts consistent with a decrease in the a lattice parameter for the B{sub 4}C-derived MgB{sub 2} as compared to an undoped sample (0.033–0.037 Å, depending on the sample). Microstructural investigation showed a three-phase mixture in the B{sub 4}C-derived ingots: MgB{sub 2−x}C{sub x} (with 0.178 < x < 0.195), MgB{sub 2}C{sub 2}, and Mg. The carbon concentration determined from the lattice parameter shift (5.95 at. %) matched well with the calorimetrically derived concentration of 5.3–5.8 at. % C. Furthermore, the carbon content measured by electron probe micro-analysis was shown to be 6.2 ± 1.3 at. %. Finally, we performed bulk specific heat measurements to determine the homogeneity of C-doping in the MgB{sub 2}. The width of the T{sub c} distribution for the C-doped MgB{sub 2} was only 3–6 K with a full-width half maximum (FWHM) of 1.4 K, compared to a width of 2.5 K and a FWHM of 0.65 for an undoped sample. The consistency of these three measurements on a large-grained homogeneous material is unambiguously supportive of C-substitution.
- OSTI ID:
- 22262545
- Journal Information:
- Applied Physics Letters, Vol. 104, Issue 16; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
Similar Records
Tuning the Superconducting Properties of Magnesium Diboride
Lead substitutions for promoted critical current density J {sub c} and mechanical properties of Mg{sub 1-x}Pb {sub x}B{sub 2} regime